An in-situ characterization method of a metal crystal cutting process

Abstract

The application discloses a kind of in-situ characterization methods of metal crystal cutting process, belong to ultra-precision machining field, including steps: step S1, preparation diamond tool: preparation diamond micron flake, use current to cut out relief surface, rake face, diamond tool polishing treatment;Step S2, preparation workpiece sample: select atomic force microscope probe, use focused ion beam micro-nano machining technology to prepare rectangular micron flake, several rectangular flake are machined in rectangular micron flake by focused ion beam, the preparation of workpiece sample is completed by using focused ion beam to blow rectangular flake;Step S3, cutting experiment: diamond tool, workpiece sample is installed in X-Nano sample rod, diamond tool is cut to workpiece sample, and bright field image, dark field image, electron diffraction pattern of the region to be measured are photographed using transmission electron microscope.The application breaks through the bottleneck that material plastic deformation and fracture behavior in turning process cannot be dynamically observed previously.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultra-precision machining, in particular to a method for in-situ characterization of metal crystal cutting process. BACKGROUND

[0002] Turning is a common machining method, which is widely used in the size machining of metal materials, and has the characteristics of high efficiency and strong forming ability. However, due to the higher requirements of high-end manufacturing field on the machining surface quality, geometric precision and material microstructure control, the traditional turning technology gradually shows limitations in these aspects. In order to realize the surface quality of sub-micron level or even nanometer level, ultra-precision turning technology emerges as the times require. At this characteristic scale, the material deformation and fracture will show completely different behaviors from the macro-scale materials, so the basic theory system such as tool wear law, workpiece deformation and removal mechanism, and non-steady evolution law of machining interface needs to be re-established.

[0003] In recent years, with the development of in-situ experiments of transmission electron microscope (TEM), researchers try to dynamically observe the plastic deformation and fracture behavior of materials at nanoscale. However, the prerequisite to achieve this goal is to develop a micro cutting system with atomic level cutting ability that can be operated in the TEM chamber. Based on the X-Nano multi-degree-of-freedom in-situ transmission electron microscope sample rod with sub-nanometer displacement control precision, a special diamond tool and workpiece sample and application method can be developed, which can be used for in-situ cutting and deformation characterization in TEM. It not only helps to reveal the real mechanical behavior of materials at a very small scale, but also provides a new technical means for atomic scale manufacturing and material science research.

[0004] At present, the method of TEM sample preparation depends on focused ion beam (FIB), and it is still a bottleneck to dynamically observe the plastic deformation and fracture behavior of materials in the turning process. SUMMARY

[0005] The purpose of the present application is to provide a method for in-situ characterization of metal crystal cutting process, which uses X-Nano system to realize the in-situ characterization of tool cutting workpiece, and aims to break through the previous bottleneck that the plastic deformation and fracture behavior of materials in the turning process cannot be dynamically observed.

[0006] To achieve the above purpose, the present application provides a method for in-situ characterization of metal crystal cutting process, comprising the following steps:

[0007] Step S1, preparing a diamond tool:

[0008] Step S11, using focused ion beam micro-nano processing technology, a diamond micron flake is prepared by digging a pit first and then U-shaped cutting, and the diamond micron flake is extracted by using an easylift needle;

[0009] Step S12, the half copper mesh is fixed, and the half copper mesh is rotated to be perpendicular to the half copper mesh and the diamond micron flake, the diamond micron flake is pasted on the half copper mesh, and a cubic block is processed after the surface treatment of the diamond micron flake, and a relief and a rake face are cut out from the cubic block by using an electric current;

[0010] Step S13, diamond tool polishing treatment;

[0011] Step S2, a workpiece sample is prepared:

[0012] Step S21, an atomic force microscope (AFM) probe is selected: a gold wire is selected and made into a loop-shaped platform with a tail, and the atomic force microscope probe is pasted on the loop-shaped platform of the gold wire by using conductive silver paste;

[0013] Step S22, using focused ion beam micro-nano processing technology, a rectangular micron flake is prepared by digging a pit first and then U-shaped cutting, and the rectangular micron flake is extracted by using an easylift needle;

[0014] Step S23, the pretreated atomic force microscope probe and gold wire assembly are pasted on one side of a focused ion beam (FIB) sample clamp, the free end of the cantilever beam of the atomic force microscope probe is flattened, and the rectangular micron flake is pasted on the top end of the cantilever beam;

[0015] Step S24, a thin area is processed on the top end of the rectangular micron flake by the focused ion beam, the top of the thin area is cut flat, a plurality of rectangular flakes are processed on the thin area, and cutting is performed on the top end and the left and right sides of the rectangular flake by using a low current;

[0016] Step S25, under the perspective of the focused ion beam looking down on the rectangular flake, the thickness of the top end of the rectangular flake is further reduced by blowing the rectangular flake by using the focused ion beam, and the preparation of the workpiece sample is completed;

[0017] Step S3, cutting experiment:

[0018] Step S31, the half copper mesh with the diamond tool is fixed on the movable end of an X-Nano sample rod, and the atomic force microscope probe and gold wire assembly with the workpiece sample are fixed on the external frame of the X-Nano sample rod;

[0019] Step S32, under a transmission electron microscope, the diamond tool is controlled by the X-Nano sample rod to cut the workpiece sample;

[0020] Step S33, the cutting area is kept in the center of the image by moving the goniometer stage of the transmission electron microscope, and the bright field image, dark field image and electron diffraction pattern of the area to be measured are taken by the transmission electron microscope.

[0021] Preferably, in step S12, several diamond micro-slices are placed on the top of the same half-copper mesh tooth, the diamond micro-slices are placed on the half-copper mesh tooth for placing the sample, part of the irradiation layer on the surface of the diamond micro-slice is removed and trimmed, a cubic block is machined on the top of the diamond micro-slice, the cubic block is used as the base of the diamond tool, a relief is obliquely cut on the top of the cubic block using a low current, a rake face is trimmed at the edge, and the wedge angle and the relief angle of the diamond tool are adjusted.

[0022] Preferably, in step S13, the prepared diamond tool is polished by using an ion thinning instrument to remove the irradiation damage layer and amorphous layer on the surface.

[0023] Preferably, in step S21, the free end of the cantilever beam of the atomic force microscope probe is directed towards the tail of the gold wire, and the atomic force microscope probe is perpendicular to the tail of the gold wire.

[0024] Preferably, in step S23, the cantilever beam of the atomic force microscope probe is vertically upward, and when the rectangular micro-slice is pasted, the atomic force microscope probe is rotated to be perpendicular to the rectangular micro-slice.

[0025] Preferably, in step S31, the free end of the cantilever beam of the atomic force microscope probe is directed towards the diamond tool on the half-copper mesh, and the axis of the cantilever beam of the tip of the atomic force microscope probe is perpendicular to the cutting direction of the diamond tool.

[0026] Preferably, in step S32, the relative position and height between the diamond tool and the workpiece sample are adjusted by displacement control through the X-Nano sample rod, the diamond tool is aligned with the workpiece sample in height, the contact between the diamond tool and the workpiece sample slice occurs on the side of the workpiece sample, the diamond tool is controlled to move along the X-axis through the X-Nano control program, and the cutting of the diamond tool on the workpiece sample is realized.

[0027] Therefore, the in-situ characterization method of the above-mentioned metal crystal cutting process has the following beneficial effects:

[0028] The application provides a method for preparing a diamond tool TEM sample and a workpiece sample with a sharp edge by using a FIB, and an in-situ characterization means for tool cutting workpiece by using an X-Nano system, which aims to break through the bottleneck that the plastic deformation and fracture behavior of materials in the turning process cannot be dynamically observed.

[0029] The technical solutions of the application are further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A flow chart of the steps of an embodiment of the in-situ characterization method of a metal crystal cutting process of the present invention;

[0031] Figure 2 A side view of a diamond tool with a wedge angle of 75 degrees prepared by a focused ion beam for an embodiment of the present invention;

[0032] Figure 3 An oblique side view of a diamond tool with a wedge angle of 75 degrees prepared by a focused ion beam for an embodiment of the present invention;

[0033] Figure 4 A side view of a diamond tool with a wedge angle of 60 degrees prepared by a focused ion beam for an embodiment of the present invention;

[0034] Figure 5 An oblique side view of a diamond tool with a wedge angle of 60 degrees prepared by a focused ion beam for an embodiment of the present invention;

[0035] Figure 6 A side view of a diamond tool with a wedge angle of 45 degrees prepared by a focused ion beam for an embodiment of the present invention;

[0036] Figure 7 An oblique side view of a diamond tool with a wedge angle of 45 degrees prepared by a focused ion beam for an embodiment of the present invention;

[0037] Figure 8 A TEM image of a diamond tool for an embodiment of the present invention;

[0038] Figure 9 A schematic diagram of a workpiece sample adhered to the top end of an AFM probe cantilever for an embodiment of the present invention;

[0039] Figure 10 A schematic diagram of four rectangular thin slices of workpiece samples machined for cutting for an embodiment of the present invention.

[0040] Figure 11 A schematic diagram of the relative positions of a diamond tool and a workpiece sample in a TEM for an embodiment of the present invention;

[0041] Figure 12 A process diagram of a diamond tool cutting a workpiece sample for an embodiment of the present invention, where a is the workpiece sample image at the start time, b is the workpiece sample image at the cutting time of 8s, c is the workpiece sample image at the cutting time of 14s, d is the workpiece sample image at the cutting time of 39s, e is the workpiece sample image at the cutting time of 63s, and f is the workpiece sample image at the cutting time of 69s;

[0042] Figure 13The bright field image in the workpiece sample cutting process of the embodiment of the present application;

[0043] Figure 14 The dark field image in the workpiece sample cutting process of the embodiment of the present application, wherein a is the dark field image of the workpiece sample cutting at the beginning, b is the dark field image of the workpiece sample cutting at the time of 91s, and c is the dark field image of the workpiece sample cutting at the time of 121s. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the embodiment of the present application more clear, the embodiment of the present application is further described in detail below in combination with the drawings and the embodiment. It should be understood that the specific embodiments described herein are only used to explain the embodiment of the present application, and are not used to limit the embodiment of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application. The examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout.

[0045] It should be noted that the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or server comprising a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0046] Similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0047] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application.

[0048] In the description of the present application, it is also necessary to explain that, unless otherwise explicitly specified and limited, the terms "arrangement", "installation", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0049] Embodiments

[0050] As Figure 1 shown, the in-situ characterization method of metal crystal cutting process according to the present application comprises the following steps:

[0051] Step S1, preparing a diamond tool:

[0052] Step S11, using diamond as the base material, using focused ion beam micro-nano processing technology, adopting the method of digging a pit first and then U-shaped cutting, a plurality of diamond micron flakes with a height of 5 μm, a width of 3 μm and a thickness of 3 μm are prepared. The easylift needle is used to extract the diamond micron flakes. The U-shaped cutting is a way of focused ion beam sample preparation technology.

[0053] Step S12, fixing the half copper mesh, rotating the half copper mesh to be perpendicular to the half copper mesh and the diamond micron flake, and then pasting the diamond micron flake on the half copper mesh. The top of the same half copper mesh tooth can place multiple diamond micron flakes, and the interval is not less than 10 μm. The half copper mesh tooth is the synapse of the half copper mesh for placing the sample, and the top end of the half copper mesh tooth is used for placing the sample. The surface of the diamond micron flake is removed partially and trimmed, and a cubic block with a height of 2 μm, a width of 2 μm and a thickness of 2 μm is processed at the top end of the diamond micron flake as the base of the diamond tool. A relief surface is obliquely cut on the top of the cubic block using a lower current (voltage of 30 kV and current of 40 pA-24 pA), and a rake surface is trimmed at the edge. Figures 2-7 As shown in the figure, the wedge angle and the relief angle of the diamond tool can be adjusted according to the actual tool.

[0054] Step S13, using an ion thinning instrument to polish the prepared diamond tool at a voltage of 0.9 kV for about one hour to remove the surface irradiation damage layer and amorphous layer. The prepared diamond tool is as shown in Figure 8 .

[0055] Step S2, preparing a workpiece sample:

[0056] Step S21, select AFM probe (model SD-T10L100). Select a gold wire with a diameter of 0.25 mm and make a U-shaped platform with a tail. Use conductive silver paste to paste the AFM probe on the U-shaped platform of the gold wire, pay attention to the free end of the cantilever beam should be towards the tail of the U-shaped platform of the gold wire, and ensure that the AFM probe is perpendicular to the tail of the gold wire.

[0057] Step S22, use focused ion beam micro-nano processing technology to prepare a rectangular micron sheet with a height of 5 μm, a width of 20 μm and a thickness of 2 μm on the workpiece sample by digging a pit first and then cutting a U-shaped way. Use easylift needle to extract the rectangular micron sheet.

[0058] Step S23, paste the pretreated AFM probe-gold wire whole assembly on one side of the FIB sample holder, and ensure that the cantilever beam of the AFM probe is vertically upward. Rotate the AFM probe to be perpendicular to the rectangular micron sheet. Flatten the top end of the free end of the cantilever beam, and paste the rectangular micron sheet on the top end of the cantilever beam, as shown in Figure 9 .

[0059] Step S24, the voltage of the focused ion beam is 30 kV, and the current is 0.79 nA-80 pA. A thin area with a height of 1 μm, a width of 20 μm and a thickness of 0.3 μm is processed on the top end of the rectangular micron sheet, and the top is cut flat. As shown in Figure 10 , four rectangular sheets with a width of 2.5 μm are trimmed on the thin area, and the mutual spacing is not less than 2 μm. Lower current (voltage 30 kV, current 7.7 pA) can be used to cut on the top end and both sides of the rectangular sheet to obtain a better test sample shape.

[0060] Step S25, under the perspective of the focused ion beam looking down on the rectangular sheet, use a voltage of 5 kv and a current of 15 pA to further reduce the thickness of the top end of the rectangular sheet by blowing it with the focused ion beam, and finally thinned to 150 μm, to complete the preparation of the workpiece sample.

[0061] Step S3, cutting experiment step:

[0062] Step S31, install the workpiece sample on the X-Nano sample rod: the X-Nano sample rod is an existing structure, and a half copper mesh with a diamond cutter is fixed on the movable end of the X-Nano sample rod. Then, the AFM probe-gold wire whole assembly with the workpiece sample is fixed on the external frame of the X-Nano sample rod, ensuring that the free end of the cantilever beam is towards the diamond cutter on the half copper mesh, and the cantilever beam axis of the tip of the AFM probe is perpendicular to the cutting direction of the diamond cutter.

[0063] Step S32, under TEM, as shown in Figure 11As shown, the relative position and height between the diamond cutter and the sample to be cut are precisely adjusted by displacement control of the X-Nano sample rod, the cutter is aligned with the sample, and contact between the diamond cutter and the sample sheet is ensured to occur on the side of the sample. Figure 12 As shown, the movement of the diamond cutter along the X-axis is precisely controlled by the X-Nano control program, and the cutting of the sample by the diamond cutter is achieved.

[0064] In step S33, the cutting area is kept in the center of the image by moving the TEM goniometer stage, and bright-field images, dark-field images, electron diffraction patterns, etc. of the area to be measured are taken by the TEM. The bright-field images during cutting are as shown in Figure 13 As shown, dislocation nucleation and slip phenomena in the sample can be observed. The dark-field images during cutting are as shown in Figure 14 As shown, the phenomenon of the cutter cutting through the grains in the sample can be observed.

[0065] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method of in-situ characterization of a metal single crystal cutting process, characterized in that, The method comprises the following steps: Step S1, preparing a diamond tool: Step S11, using a focused ion beam micro-nano machining technology, a diamond micron flake is prepared by digging a pit first and then U-shaped cutting, and the diamond micron flake is extracted by using an easylift needle; Step S12, fixing a half copper mesh, rotating the half copper mesh to be perpendicular to the half copper mesh and the diamond micron flake, and pasting the diamond micron flake on the half copper mesh, and processing a cubic block on the surface of the diamond micron flake, and cutting a relief surface and a rake surface on the cubic block by using an electric current; Step S13, polishing the diamond tool; Step S2, preparing a workpiece sample: Step S21, selecting an atomic force microscope probe: selecting a gold wire, making it into a back-shaped platform, and pasting the atomic force microscope probe on the back-shaped platform of the gold wire by using conductive silver paste; Step S22, using a focused ion beam micro-nano machining technology, a rectangular micron flake is prepared by digging a pit first and then U-shaped cutting, and the rectangular micron flake is extracted by using an easylift needle; Step S23, pasting the pretreated atomic force microscope probe and gold wire assembly on one side of the focused ion beam micro-nano cutting sample clamp, flattening the free end of the cantilever beam of the atomic force microscope probe, and pasting the rectangular micron flake on the top end of the cantilever beam; Step S24, processing a thin area on the top end of the rectangular micron flake by using a focused ion beam, cutting the top of the thin area, processing a plurality of rectangular flakes on the thin area, and cutting the top end and the left and right sides of the rectangular flakes by using a low current; Step S25, under the perspective of the focused ion beam, the thickness of the top end of the rectangular flake is further reduced by blowing the rectangular flake by using the focused ion beam, and the preparation of the workpiece sample is completed; Step S3, cutting experiment: Step S31, fixing the half copper mesh with the diamond tool on the movable end of the X-Nano sample rod, and fixing the atomic force microscope probe and gold wire assembly with the workpiece sample on the external frame of the X-Nano sample rod; Step S32, under the transmission electron microscope, the diamond tool is controlled by the X-Nano sample rod to cut the workpiece sample; Step S33, the cutting area is kept in the center of the image by moving the transmission electron microscope goniometer stage, and the bright field image, dark field image and electron diffraction pattern of the area to be measured are photographed by using the transmission electron microscope.

2. The method of in-situ characterization of metal single crystal slicing process according to claim 1, characterized in that: In step S12, a plurality of diamond micron flakes are placed on the top end of the same half copper mesh, the diamond micron flakes are placed on the half copper mesh teeth for placing samples, part of the irradiation layer on the surface of the diamond micron flake is removed and trimmed, a cubic block is processed on the top end of the diamond micron flake, the cubic block is used as the base of the diamond tool, the relief surface is obliquely cut on the top of the cubic block by using a low current, the rake surface is trimmed at the cutting edge, and the wedge angle and the relief angle of the diamond tool are adjusted.

3. The method of in-situ characterization of metal single crystal slicing process as claimed in claim 1, wherein: In step S13, the prepared diamond tool is polished by using an ion thinning instrument to remove the surface irradiation damage layer and amorphous layer.

4. The method of in-situ characterization of metal single crystal slicing process according to claim 1, characterized in that: In step S21, the free end of the cantilever beam of the atomic force microscope probe faces the tail of the gold wire, and the atomic force microscope probe is perpendicular to the tail of the gold wire.

5. The method of in-situ characterization of metal single crystal slicing process as claimed in claim 1, wherein: In step S23, the cantilever beam of the atomic force microscope probe is vertically upward, and the rectangular micron sheet is pasted, the atomic force microscope probe is rotated to be perpendicular to the rectangular micron sheet.

6. The method of in-situ characterization of metal single crystal slicing process as claimed in claim 1, wherein: In step S31, the free end of the cantilever beam of the atomic force microscope probe is directed to the diamond cutter on the half copper mesh, and the cantilever beam axis of the atomic force microscope probe tip is perpendicular to the cutting direction of the diamond cutter.

7. The in-situ characterization method of a metal single crystal cutting process according to claim 1, characterized in that: In step S32, the relative position and height between the diamond cutter and the workpiece sample are adjusted by displacement control of the X-Nano sample rod, the diamond cutter is aligned with the workpiece sample, the contact between the diamond cutter and the workpiece sample sheet occurs on one side of the workpiece sample, and the diamond cutter is controlled to move along the X axis by the X-Nano control program, so that the diamond cutter cuts the workpiece sample.

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